We have this one. Loki loves it. He treats it like his crate and when I put him in there it is time for a nap! It even makes getting in and out of the car a little safer because I can leave him strapped in until I'm ready to take him out. Plus, of course it is safer for crashes but I find it very handy just for daily use.
http://www.amazon.com/Pet-Stow-Away-.../dp/B000634MJG
PS This one is a little bigger for the bigger pups, although my friend just got one for her 2 pounder and she loves it too.